IIRC it happened at Swan Hunter's on Tyneside - over an Easter weekend - maybe in the early 60's
In those far off days they had a line of propellors (all phosphor bronze) lined up on the dock side - this was well before just-in-time-delivery
Someone turned up with a low-loader and escort vehicle and all the paper-work saying it was to go to Clydeside and they even dug out the duty crane operator to move it......
it was 20-40 tons and worth a fortune ... and was never seen again
clearly an inside job and probably middle management but no oen was ever fingered for it...................